(1) Field of the Invention
The present invention relates generally an apparatus for treating fibrous materials, such wood-based cellulosic fibers; nonwood-based cellulosic fibers; natural textile fibers, and man-made fibers and, more particularly, to an apparatus for treating cellulosic fibrous material for subsequent processing into thermal and acoustic loose-fill installation.
(2) Description of the Prior Art
Each waste paper (WP) treatment plant is specifically designed to raise the quality of the input WP grades up to the quality required for subsequent use. This goal includes enabling the lowest practical quality of WP grade to be used. System designers ought to consider the WP treatment plant as an entity—not just the influence of each individual piece of equipment.
In WP treatment plants for converting WP to cellulosic insulation, traditionally dry processing has been used. Over the years, a variety of dry mills have been used to break down WP and remove prohibitive materials. Prohibitive materials (“prohibitives”) are materials other than paper (e.g., plastic, metal, glass, etc.) (a.k.a. “contraries” in the paper recycling industry). Some dry mills have involved high-energy impact devices. Other dry mills have involved grinding WP down to the smallest particle size, sometimes even all the way to fiber. These size reduction processes tend to be high mechanical energy and high horsepower type of processes. Also, these processes tend to generate a lot of dust. Moreover, these processors are not robust because input WP must be of a quality that contains limited amounts, types, and size of prohibitives. The use of the high mechanical energy makes it important to eliminating any prohibitives from these processes that may facilitate sparking.
Even after eliminating any prohibitives that may facilitate sparking, it is still important in dry processing to add fire retardants to the WP. Apart from making the cellulosic insulation fire resistant, it is desirable to make the WP fire resistant as it is being processed into a finished product to prevent fire. Fires may consume WP before it is processed into a finished product. Also, fires tend to disrupt production in the plant process stream. To that end, fire retardants such as boric acid or ammonium sulfate, may be added to the WP. Traditionally, fire retardants have been added as powders, or sometimes, as liquid sprayed onto the dry WP at some point in the plant process stream. A disadvantage with adding fire retardants as liquid is that a means for drying the WP must be worked out since WP treatment plants for converting WP to cellulosic insulation tend not to have dryers.
An approach to trying to eliminate some of the above-mentioned problems has been to use a Continuous Batch Fiber Recovery System (CBFRS, Regenex). This approach does not fit neatly into traditional paper industry WP treatment approaches because it comes from the laundry industry, where it has been used for more than 15 years.
In CBFRS, a tunnel washer having a battery of basic modules is used. Collectively, these modules function initially like a drum pulper, and subsequently like a de-inking washer. The modules also permit bleaching, either during de-inking or following pulping.
The basic module consists of a rotating inner cylinder and an outer screen shell. The rotating inner cylinder includes a scoop that rocks through 230° initially, then through 360°, and so transfers process WP to the next module. This continual dropping action separates prohibitives from WP to yield good fiber. The prohibitives are discharged from the end of the cylinder. The outer screen shell accepts separated good fiber during the WP bale re-pulping stage, and allows ink to pass through during any de-inking washing stage. The complete system requires some additional items, such as screens, and may be a wet lap de-watering device. A clarifier provides water closure. Ash, ink particles and other prohibitives are removed so that the water can be re-circulated to the tunnel washer. Among the disadvantage of CBFRS are equipment expense and the slowness of that process.
Thus, there remains a need for a new and improved apparatus for treating fibrous material which is sufficiently robust so as to be able to accommodate a broad spectrum of input materials and, more particularly, to an apparatus for liquid-based cellulosic fiber separation for subsequent processing into, for example, loose-fill insulation.